Rotary steam engine

ABSTRACT

By rotatably mounting a hollow cylindrical drum valve with an internal eccentric rotor with a plurality of vanes dividing the annular space between the drum valve and the rotor into a plurality of fluid tight compartments and coupling the rotor and drum valve to rotate in unison about their respective eccentric axes, pressurized steam admitted to the several compartments when they are at a minimum displacement can expand by causing these connected elements to rotate as a steam pressurized compartment increases in volume and thus delivers useful torque through a connected drive shaft. Because the net reaction area of a compartment increases as the volume of a compartment increases, the decreasing steam pressure has a progressively larger net reaction surface as the compartment progresses towards its maximum displacement.

United vStates Patent [191 Granberg [4 Apr. 23, 1974 1 ROTARY STEAM ENGINE Primary ExaininerC. J. Husar [76] Inventor: Albert J. Granberg, 6178 Estate Dr, Qakl d m 94 1 fittorrrey, Agent, or Firm-Fryer, Tjensvold; Phillips & r em 10 221 Filed: Apr. 13, 1973 p By rotatably mounting a hollow cylindrical drum valve 2% F' 'i fi sg 88 with an internal eccentric rotor with a plurality of 8 3 l vanes dividing the annular space between the drum 1 d 0 Search 1 /1 l l valve and the rotor into a plurality of fluid tight com- 418/258 266 partments and coupling the rotor and drum valve to rotate in unison about their respective eccentric axes, pressurized steam admitted to the several compart- [56] References Cited ments when they are at a minimum displacement can expand by causing these connected elements to rotate UNITED STATES PATENTS as a steam pressurized compartment increases in vol- 456,351 7/1891 Adams .[418/258 ume and thus delivers useful torque through a con- Real/e et a].

drive shaft Because the net-reaction area of a 3 compartment increases as th'e volume of a compart- 3,l93,19O 741965 Hesse; 418/131 X ment increases, the decreasing steam pressure has a 5/1970 n progressively larger net reaction surface as the com- Yamauchi l23/8.0l X

partment progresses towards: its maximum displacement.

9 Claims, 4 Drawing Figures 7 t 1 ROTARY STEAM ENGINE BACKGROUND OF THE INVENTION The current invention is related to the positive dis placement fluid translating device disclosed and steam engines still remain competitive, because a steam cycle can take devices in of the changes. in fluid state, and therefore been quite a change in state can be substitutedfor the isotherm an electrical of the fixed gas Carnot cycle; As a result the utilization of steam for power continues to be employed in a number of situa tions', particularly in industrial power generationapplications. Further steam power is currently being reconsidered for powering pullutionfree vehicles,

Therefore it is an object of the current invention to provide a compact and economical rotary steam engine forapplications in which steam can be efficiently and effectively utilized. anitem Also, it;is an object to provide an improved steam engine wherein the net reaction area increases as ac ontained volume of steam expands therein to better utilize the progressively decreasing pressure of the steam ,during-this expansion.

Another object is the provision of a rotary steam engine with a minimum number of parts and {which also has a comparatively long, trouble-free service life.

Otherobjects andadvantages of the rotary steam en gine will be apparent from the drawings and the following description. 7

I SUMMARY or THIS INVENTION I A closed cycle rotary steam engine which has :the abovea'dvantages includes asupportcase with a steam inlet, an exhaust outlet and a cylindrical bore which receives a hollow cylindrical drum valve that sealingly enthe drive shaft and the drum valve necessitated by their eccentric mountings and off-set respective axes of rotation.

DESCRIPTION OF A PREFERRED EMBODIMENT 12 with a cylindrical valve wall 13. As can be seen in FIGS. -1 and 2, one side of the valve wall includes a large semi-circular depressed exhaust port 14 which is in communication with the exhaust outlet 15 that is 10- cated near the top .of the case. Opposite the exhaust port on the other side of the case in the valve wall are several small inlet apertures, i.e., the main steam aper- V -ture 1.6 and the auxiliary steam aperture 17, both of which ,are in fluid communication with the steam inlet 18, via passages 19 and 20, respectively. The latter'passage, connected to the auxiliary aperture, includes a valve cock 21 which can be rotated with handle 22'to regulate the .flow of steam to the auxiliary aperture from afull open condition to a complete shut-off condition. This dual inlet aperture arrangement which is employed during starting will be subsequently described with reference to the operation of the rotary steam engine. Also, handle 22 can regulate passage 19, v

In the embodiment shown in the drawingsthe case 1 1 has radially projecting flanges 23 at its opposite ends to which the other case componentsof the engine can be attached. For example, the rear end plate 24 is bolted to the rear radial'flange with bolts 25 and includes a central stub bearing shaft 26 in which drive shaft 27. has

. its inboard end ,eccentrically journaled for rotation.

gages the wall of the bore with the drum valve supported'for rotation at the oppositeends of the case and a smaller cylindrical rotor element eccentrically disposed within the .drum valveso that its rectangular vanes, reciprocally'mounted in grooves formed in .the rotor element, divide the annular space between the drum valve and rotor element into ,a plurality .of substantially fluid tight compartments, each .of which alternately communicates with the inlet and outlet through ports formed inthe surface of the.,drum valve so a drive shaft keyed to the rotor element and coupled to the drum valve will deliver torque when steam is admitted to :these several compartments at their minimum displacement and then allowed to expand :therein until they reach their maximum displacement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective showing the major components of the rotary steam engine;

FIG. 2 is a cross section through the central portion of the rotary steam engine;

FIG. 3 is .a longitudinal sectional view of the rotary steam engine showing its various components in their assembled position; and- FIG. 4 is an end elevation of the .drum valve and .its forward bearing hub and showing the coupling between A hollowdrum valve 30 is fitted into the bore 12so that its outer cylindrical surface 31 slidingly engages the valve wall 13 of the bore when its rear bearing hub 32 is telescopingly received on the rear stub bearing shaft 26 and abuts against a thrustibearing 33. This thrust bearing is supported by the end plate at the base of the stubbearing shaft. Through this arrangement the drum valve is supported for rotation within the bore of the case on the resulting journal formed at the rear thereof and effectively seals the exhaust port 14 and the inlet apertures 16 and 17 from direct communica- 7 tion' with one another. I

As can be seen in FIGS. 1 and 2, the rear bearinghub 32 protrudes from the rear'wall of the drum valve, and at the forward end of the drum valve, a radial flange 34 is formed to which the drum cover 35 is attached with bolts 36 to close the open end of the hollow drum valve. Because of the presence of the flange .on the forward end .of the drum valve the bore 12 is stepped to a larger diameter 12 so that the flange of the drum valve will fit intoflthe bore when the drum valve is .mounted in the case. At opposite ends of the bore 12 carbon seals 37 are inserted into grooves in the valve wall 13 to prevent the leakage of steam axially along outer cylindrical surface of the drum valve.

With the drum valve 30 mounted in the bore 12 as described above, major ports 40 centrally formed in its outer surface will communicate sequentially with the inlet apertures 16 and 17' and the exhaust port 14, as the drum valve turns within the .bore, thereby allowing inlet steam to enter the interior of the drum valve and be exhausted therefrom. Minor ports 41 are also formed in the surface of the drum valve and offset from the major ports (as can be seen in the drawings) so they can only communicate with the exhaust port as the drum valve rotates. The function of the minor ports is to bleed exhaust steam from the drum valve after its associated major port has closed off the communication with the exhaust port and while an associated compartment formed within the drum valve is still decreasing in volume. This arrangement will be more fully discussed with regard to the operation of the rotary steam engine.

In the embodiment shown in the drawings the major and minor parts are formed with their centers 120 apart and also withthe minor ports circumferentially offset from the major ports, as can best be seen in FIG. 1.

To prevent the inlet steam from passing directly to the exhaust port 14 via the several major ports 40 in the surface of the hollow drum valve 30, the latter is divided into three substantially fluid tight compartments each having a major port and a minor port 41 in communication therewi th. This is accomplished with an internal rotor element 50 of a diameter smaller than the inner diameter of the hollow drum valve 30 so the rotor element can be eccentrically mounted within the drum valve on a drive shaft 27 that passes through the ends of the drum valve and through the rotor element as indicated in the drawings. This mounting arrangement 1 leaves an annular space of varying cross section between the outer surface of the rotor element and the inner cylindrical surface of the hollow drum valve as can be seen in FIG. 2. The three individual substantially fluid tight compartments are completed with radial vanes 51 that divide the annular space into separate compartments by reciprocally mounting these vanes in axial slots running the length of the rotor element and v biasing them outwardly with several cylindrical springs 53 at opposite ends of the rotor element. These springs engage the inner edges 54 of the several vanes and urge them outwardly so their outer edges 55 bear against the inner cylindrical wall 56 of the drum valve. Recesses 57 formed in opposite ends of the rotor element form a pocket for the springs and have a large inner opening so that the cylindrical springs can adopt a position within the recess which is substantially concentric with the drum valve, as can be seen in the drawings.

As aresult of the above arrangement the vanes will be held against the inner cylindrical surface of the drum valve as the rotor element rotates with the vanes reciprocating in the axial slots to accommodate the eccentric mounting arrangement of the rotor element relative to the drum valve. To ensure fluid tight compartments the radial end faces of the rotor element, having the recesses for the cylindrical springs, sealingly engage the inner end surfaces of the drum valve when its cover is bolted thereon and the lengths of the several vanes are machined to engage these same surfaces to form the compartments.

Drive shaft 27, which eccentrically supports the rotor I element 50 within the drum valve 30, is keyed to the rotor element so they rotate in unison and are supported on the journal in stub bearing shaft 26, described above. To ensure the proper relationship between the drum valve and the vanes of the rotor element within the drum valve, the latter is also connected to the drum shaft with a heavy duty coupling unit 60 so that all these three parts are timed to rotate in unison. This coupling includes a coupling bar which has an aperture through which the drive shaft passes and a set screw 61 (see FIG. 4) which locks the drive shaft in the coupling bar after it has been mounted adjacent to the outer surface of the drum plate 35. A radial notch 62 is formed in one end of the coupling bar and when the bar is mounted on the drive shaft, a bearing busing 63 mounted on a pin shaft 64, projecting from the face of the drum plate, is received in this notch, as can be seen best in FIG. 3. Since the axis of rotation of the drum valve differs from the axis of rotation of drive shaft 27 the bushing and associated pin shaft will reciprocate in the notch as these several parts rotate their respective axes.

The coupling unit 60 is located in a U-shaped bearing housing 65 that is affixed to the face of the drum plate by welding in a manner that its legs 66 straddle the coupling unit, as best can be seen in FIG. 4. The bearing housing is precisely located before welding with guide pins 68, so that the forward bearing hub 67 of the drum valve is aligned with the rear bearing hub 32 previously described, and the outboard end of pin shaft 64.is received in an aperture 69 in the top of the bearing housing. This arrangement strengthens the structural integrity of the coupling unit since it can be subject to rather high torque loadings during the operation of the rotary steam engine. Through the use of the bearing bushing on the pin shaft the sliding friction forces are reduced in the coupling unit during such loadingsr A bell housing 70 mounts on the forward radial flange 34 of the case 11 with bolts 71 to close the forward end of the case and includes a forward stub bearing shaft 72 on which the forward bearing hub 67 is telescopingly received so that it abuts against a thrust bearing 73. This bell housing includes a bore 74 through which drive shaft 27 passes and it can be seen that the drive shaft bow is eccentric to the cylindrical axis of the forward stub bearing shaft. From the above description, it can be appreciated that the drum valve is supported at both ends of the case for rotation so that unusually high frictional loadings cannot develop between its outer surface and the cylindrical valve wall 13, as drum valve rotates within the bore 12. In certain embodiments of this invention more sophisticated bearings can be employed for the various journals described above and such improved bearing designs are within the scope of the described invention.

As indicated the drive shaft passes through the bell housing 70 and projects forward therefrom, as can be seen in FIG. 3. To form a seal along the drive shaft 8. gland flange 78 with an aperture 79 for the drive shaft is mounted on the forward end of the bell housing with bolts 80. Within the gland flange an annular recess 81 contains packing 82 to prevent steam leakage along the drive shaft 27 as it'rotates.

With the rotary engine completely assembled, pressurized steam can be admitted to the steam inlet 18 and pass through passages 19 and 20 to inlet apertures 16 and 17 respectively in the inner valve wall 13 of the bore, when valve cock 21 is open. Through utilization of center spacing the major ports 40 in the outer surface of the drum valve, prssurized steam will be admitted to at least one of the three chambers within the drum valve at a time when such a chamber is at or, near its minimum displacement. This condition is insured by eccentrically locating the rotor element 50 near the top of the case 11, as can best be seen in FIG. 2 and by 10- cating the inlet apertures 16 and l7'and the exhaust port 14 on opposite sides of the case, as illustrated. Be-

cause of the eccentricity of the mounting of the rotor element there is a net reaction force in each compartment due to the steam pressure acting on the larger exposed vane surface operating to rotate the drum valve in the direction indicated by arrow A on FIG. 2. When the engine is running valvecock 21 may be closed so that steam is admitted only via passage 19 and the main steam inlet aperture 16. Once the trailing edge 40a of a major port 40 closes off inlet aperture 16 the valve wall 13 effectively closes the compartment and a contained volume of pressurized steam is enclosedwithin the compartment. This steam can continue to expand creating a net reactionpressure to rotate the drum and its connected drive shaft until the compartment reaches its maximum displacement .and the leading edge 40b of the main port of the compartment comes into communicaion with exhaust port 14. Obviously the pressure of the confined volume of pressurized steam will decrease as the volume ofthe chamber increases due to rotation of the drum valve, but so long as the pressure in the chamber is above ambient pressure a net reaction force will be acting to rotate the drum valve, rotor and drive shaft. F urthe r, as this compartment increases in volume due to the rotation, the net reaction area also increases, so a progressively lower steam pressure therein will .act on a progressively increasing reaction area until the leading vane of this compartment reaches the bottom of the case.

After a major port comes into communication with the exhaust port 14 the volume of its associated compartment begins to decrease as the rotation of the drum valve continues. This condition does not cause a problem as long as the major port is in communication with the exhaust port. However, when the trailing edge of the major port closes off its compartment from the exhaust port, and the volume of the chamber is still decreasing in the design illustrated, pressure could build up in the compartment. To prevent this condition the minor ports, one of which is located aft of the trailing edge of each major port of each compartment, vent the compartment to the exhaust port during this condition to prevent pressure build-up. Subsequently on continued rotation of the valve drum the minor port passes onto the valve wall 13 and is closed until rotation continues sufficiently to bring it back into communication with the exhaust port. 1 i

As indicated above, each minor port 41 is offset from its associated major port 40 so that it only registers with the exhaust port 14 and is otherwise closed by the valve wall 13 of the bore. Thus a substantially fluid tight steam expansion compartment is formed within the drum valve of a rotary steam engine as the major ports are also sealed by the valve wall when not in communication with the inlet apertures.

Because of the location of the main steam inlet aperture l6 and its limited communication with the major ports, it is possible that the engine might stop so it is not in communication with any of the major ports. As a result the auxiliary port 17 can be employed to start the engine by opening valve cock 21 to the position shown in FIG. ,2.

Obviously, a rotary steam engine of this type would be encased in appropriate insulation to avoid loss of efficiency through unnecessary heat loss, and only the basic components are illustrated and described herein. Further, steam condensation within the engine should 6 not be a problem since the minor ports vent each compartment until it ceases to decrease in volume thereby preventing a hydraulic lock by condensed steam (water) within a compartment.

Also, the rectangular vanes can include sealing strips along their edges to improve their sealing relationship with the inner surfaces of the drum valve, as there is only limited sliding movement between the several vanes and the drum valve.

What is claimed is:

1.,A closed cycle rotary steam engine comprising:

a case having a steam inlet, an exhaust outlet and a bore with a cylindricalvalve wall, said outlet having fluid communication with a large semi-circular depressed exhaust port formed in said valve wall surface and said inlet having fluid communication with several inlet apertures in said valve wall oppo-.

site said depressed exhaust port;

a hollow cylindrical drum valve slidingly engaging said cylindrical valve wall in a sealing relationship, said drum valve having a plurality of equally spaced major and minor ports in its outer surface, each said major ports arranged to intermittently communicate withboth said exhaust port and said inlet apertures and each of said minor ports arranged to intermittently communicate with'only said exhaust port as said cylindrical drum valve rotates in said 'case on bearings supporting'said drum valve therein; a cylindrical rotor element eccentrically disposed inside said drum valve having radially oriented surfaces-at its opposite ends whichsealingly engage the contiguous inner end surfaces of said drum valve, said cylindrical rotor element having a concentric aperture therein;

a drive shaft having an end projecting from said case and passing through said drum valve and said concentric aperture of said cylindrical rotor element mounting it eccentrically within said drum valve and leaving an annular space therebetween;

a plurality of rectangular vanes reciprocally mounted in lengthwise grooves in said rotor element, each of said vanes having innerv and outer edges with said vanes disposed'in said rotor element to divide said annular space into a plurality of substantially fluid I ftight compartments, each compartment having a major port and a minor port :in fluid communication therewith;

circular floating spring means within said rotor element bearing against said inner edges of said vanes and operable to hold their outer edges against the inner cylindrical surface of said drum valve;

key means locking said drive shaft with said rotor element; and 1 coupling means connecting said drive shaft to said drum valve for timed rotation and operable to compensate for the eccentricity of their respective rotational axes whereby steam admitted to said inlet will enter said compartments when they are at a minimum displacement and cause said connected element to rotate and deliver torque throughsaid drive shaft as it expands in the said compartments.

2. The closed cycle steam engine defined in claim 1 wherein the major ports in the drum valve are on centers. i

3. The closed cycle steam engine as defined in claim lwherein the inlet apertures include a major inlet aperture and an auxiliary inlet aperture with said auxiliary inlet aperture independently controlled by a valve means.

4. The closed cycle steam engine as defined in claim 1 wherein the rectangular vanes have sealing means along their edges contiguous to the surfaces of the drum valve.

5. The closed cycle steam engine as defined in claim 1 wherein a control valve is connected between the several inlet apertures and the steam inlet is operable to regulate the flow of inlet steam in either of said inlet apertures simultaneously and independently.

6. The closed cycle steam engine as defined in claim 5 wherein the control valve is a rotary valve.

7. The closed cycle steam engine as defined in claim 1 wherein the coupling means includes a bar-like member with a notch formed therein and an aperture for receiving and locking the drive shaft therein along with a bushing mounted on the drum valve and received in said notchto allow eccentric timed rotation of said end of the cylindrical drum for rotation within the case. 

1. A closed cycle rotary steam engine comprising: a case having a steam inlet, an exhaust outlet and a bore with a cylindrical valve wall, said outlet having fluid communication with a large semi-circular depressed exhaust port formed in said valve wall surface and said inlet having fluid communication with several inlet apertures in said valve wall opposite said depressed exhaust port; a hollow cylindrical drum valve slidingly engaging said cylindrical valve wall in a sealing relationship, said drum valve having a plurality of equally spaced major and minor ports in its outer surface, each said major ports arranged to intermittently communicate with both said exhaust port and said inlet apertures and each of said minor ports arranged to intermittently communicate with only said exhaust port as said cylindrical drum valve rotates in said case on bearings supporting said drum valve therein; a cylindrical rotor element eccentrically disposed inside said drum valve having radially oriEnted surfaces at its opposite ends which sealingly engage the contiguous inner end surfaces of said drum valve, said cylindrical rotor element having a concentric aperture therein; a drive shaft having an end projecting from said case and passing through said drum valve and said concentric aperture of said cylindrical rotor element mounting it eccentrically within said drum valve and leaving an annular space therebetween; a plurality of rectangular vanes reciprocally mounted in lengthwise grooves in said rotor element, each of said vanes having inner and outer edges with said vanes disposed in said rotor element to divide said annular space into a plurality of substantially fluid tight compartments, each compartment having a major port and a minor port in fluid communication therewith; circular floating spring means within said rotor element bearing against said inner edges of said vanes and operable to hold their outer edges against the inner cylindrical surface of said drum valve; key means locking said drive shaft with said rotor element; and coupling means connecting said drive shaft to said drum valve for timed rotation and operable to compensate for the eccentricity of their respective rotational axes whereby steam admitted to said inlet will enter said compartments when they are at a minimum displacement and cause said connected element to rotate and deliver torque through said drive shaft as it expands in the said compartments.
 2. The closed cycle steam engine defined in claim 1 wherein the major ports in the drum valve are on 120* centers.
 3. The closed cycle steam engine as defined in claim 1 wherein the inlet apertures include a major inlet aperture and an auxiliary inlet aperture with said auxiliary inlet aperture independently controlled by a valve means.
 4. The closed cycle steam engine as defined in claim 1 wherein the rectangular vanes have sealing means along their edges contiguous to the surfaces of the drum valve.
 5. The closed cycle steam engine as defined in claim 1 wherein a control valve is connected between the several inlet apertures and the steam inlet is operable to regulate the flow of inlet steam in either of said inlet apertures simultaneously and independently.
 6. The closed cycle steam engine as defined in claim 5 wherein the control valve is a rotary valve.
 7. The closed cycle steam engine as defined in claim 1 wherein the coupling means includes a bar-like member with a notch formed therein and an aperture for receiving and locking the drive shaft therein along with a bushing mounted on the drum valve and received in said notch to allow eccentric timed rotation of said drive shaft and said drum valve.
 8. The closed cycle steam engine as defined in claim 7 wherein the coupling means also included a U-shaped bearing housing affixed to the cylindrical drum in which the bar-like member is received and which supports the end of the bushing remote from the drum plate to improve the torque transmitting capacity between the drive shaft and said cylindrical drum.
 9. The closed cycle steam engine defined in claim 8 wherein the U-shaped bearing housing supports one end of the cylindrical drum for rotation within the case. 